Situations exist where it is desirable to deploy a covert device such as a camera or other suitable device in a tunnel, ventilation shaft, corridor, or other passage. For example, a digital camera may be deployed in a ventilation shaft to observe a suspect or individual who is at a location near an opening in the ventilation shaft. The camera then relays captured digital information back to a user or device of the system through an RF (radio frequency) transmission. The user or device is typically external to the passage where the spy or observation operation is taking place. Such an application, however, is not limited to spy applications. For example, a user of such a system may desire to monitor conditions in an otherwise hostile environment such as a coal mining shaft or other dangerous location by deploying a camera or other device within the shaft, and then relaying information to a user or device external to the shaft.
In such a situation as described above, difficulty arises when attempting to transmit the information back out of the passage. Specifically, the walls of the passage may interfere with the transmission. Also, if the signal strength is increased to a level which is able to penetrate the walls of the passage, such a signal may be intercepted or may require an unrealistic amount of power to generate. As such, the deployment of relays or nodes is sometimes used to establish a communication network between the user or device external to the shaft and the camera or device in the passage. The nodes can be deployed by using a robot or other suitable means which travels down a passage and deploys the nodes from a position where the camera or other device is located to a position where transmission may be received by the user or device external to the passage. The nodes are spaced from each other such that, each node is able to maintain an RF communication link with the adjacent nodes. By this way, information from the device or camera inside the passage may be relayed to the device or user external to the passage. The camera or device is then able to transmit information, such as optical or viewing information from a camera, back to an individual or controller outside the passage.
While the above identified solution does allow the transmission of information at a reduced RF signal strength, some drawbacks exist. Specifically, there still exists a possibility that the RF signal may be intercepted depending on the space of the nodes. One solution to the above identified problem is to string a shielded cable or other similar transmitting means from the internal device to the external device or user, instead of using the RF nodes as described above. However, the logistics of using such a string or cable creates difficulty as such a cable may be visually observed and also may break or get hung along the passage. The present invention was developed in light of these and other drawbacks.